In the summer of 1975 a conference on "The Effects of Noise on Hearing: Critical Issues", was held in Syracuse, New York. The conference, sponsored by NIOSH, was attended by over 150 scientists, clinicians and government officials who are involved with problems of noise and its effect on hearing. The direct product of the conference was a book summarizing the results of the symposium proceedings. This volume has received very positive reviews (see Appendix A) and it now serves as a valuable reference test for scientists and government officials dealing with noise problems. Since the original symposium, and perhaps because of it, there have been a number of relevant research findings that have important implications for audiological diagnoses and ultimately noise standards. Furthermore, progress has been made on demographics of industrial noise induced permanent threshold shift (NIPTS), especially in several European countries. In light of these findings, the authors propose a three-day symposium to provide a forum for discussing new basic science and demographic data which are specifically germane to the issue of noise standards and hearing hazards. Special emphasis is to be given to impulse noise. The proceedings of this conference, containing approximately 25 summary papers arranged in five chapters (as outlined in this proposal) will be published and made widely available through a commercial publishing firm (Raven Press).